Small antenna apparatus operable in multiple frequency bands

Abstract

A first base radiation element has a first end connected to the feed point, and a second end. A second base radiation element has a first end connected to the ground point, and a second end. The first and second base radiation elements respectively include portions extending in a first direction and close to each other. The first base radiation element is branched into first and second branch radiation elements at a first branch point located at the second end of the first base radiation element, the first branch radiation element includes a portion extending in the first direction, and the second branch radiation element includes a portion extending in a second direction opposite to the first direction. The end of the second base radiation element is connected to a connecting point different from the first branch point of the first branch radiation element.

The invention claimed is: 
     
       1. An antenna apparatus comprising:
 a feed point; 
 a ground point; 
 a first base radiation element and a second base radiation element; and 
 a connecting element, 
 wherein the first base radiation element has a first end and a second end opposite to the first end, and extends between the first and second ends of the first base radiation element, the first end of the first base radiation element is connected to the feed point, and the first base radiation element includes a first portion extending in a +x direction, and a second portion including the second end of the first base radiation element, and the second portion extends in a +z direction and a +v direction continuously, 
 wherein the second base radiation element has a third end and a fourth end opposite to the third end, and extends between the third and fourth ends of the second base radiation element, the third end of the second base radiation element is connected to the ground point, the second base radiation element includes a third portion extending in the +x direction, and a fourth portion including the fourth end of the second base radiation element, and the fourth portion extends in the +x direction and the +z direction continuously, 
 wherein the first end of the first base radiation element is closer to the third end of the second base radiation element than to the fourth end of the second base radiation element, and the second end of the first base radiation element is closer to the fourth end of the second base radiation element than to the third end of the second base radiation element, 
 wherein the first portions of the first base radiation element and the third portion of second base radiation element are parallel to each other and spaced at a predetermined distance from each other in the +y direction, 
 wherein the connecting element has a fifth end and a sixth end opposite to the fifth end, and extends between the fifth and sixth ends of the connecting element, the fifth ends of the connecting element is connected directly to the second end of the first base radiation element, the sixth end of the connecting element is connected directly to the fourth end of the second base radiation element, and the connecting element extends in the +x direction, and 
 wherein the second portion of the first base radiation element, the fourth portion of the second base radiation element and the connecting element constitute a loop configuration electrically, and the first and second base radiation elements are electrically connected to each other only through the connecting element. 
 
     
     
       2. The antenna apparatus as claimed in  claim 1 , further comprising:
 a first branch radiation element and a second branch radiation element, 
 wherein the first base radiation element is branched into the first and second branch radiation elements at a first branch point located at the second end of the first base radiation element, the first and second branch radiation element are open-ended, the first branch radiation element includes a portion extending in the first direction from the first branch point, and the second branch radiation element includes a portion extending in a second direction from the first branch point, and the second direction is opposite to the first direction, and 
 wherein the connecting element is a part of the first branch radiation element. 
 
     
     
       3. The antenna apparatus as claimed in  claim 2 ,
 wherein the first and second base radiation elements and the first branch radiation element resonate at a first frequency, and 
 wherein the second branch radiation element resonates at a second frequency higher than the first frequency. 
 
     
     
       4. The antenna apparatus as claimed in  claim 2 , further comprising a third branch radiation element branched at a second branch point on the first base radiation element,
 wherein the third branch radiation element is open ended, and the third branch radiation element includes a portion extending in the first direction from the second branch point. 
 
     
     
       5. The antenna apparatus as claimed in  claim 4 ,
 wherein the first and second base radiation elements and the first branch radiation element resonate at a first frequency, 
 wherein the second branch radiation element resonates at a second frequency higher than the first frequency, and 
 wherein the third branch radiation element resonates at a third frequency higher than the second frequency. 
 
     
     
       6. The antenna apparatus as claimed in  claim 4 ,
 wherein parts of the respective first and third branch radiation elements are capacitively coupled to each other. 
 
     
     
       7. The antenna apparatus as claimed in  claim 4 , further comprising:
 a first coupling element extending along the second branch radiation element and integrally formed with the second branch radiation element; and 
 a second coupling element extending along the second base radiation element and integrally formed with the second base radiation element, 
 wherein the first and second coupling elements are capacitively coupled to each other. 
 
     
     
       8. The antenna apparatus as claimed in  claim 7 , further comprising a third coupling element extending along the first base radiation element and integrally formed with the first base radiation element,
 wherein the third coupling element is capacitively coupled to at least one of the first and second coupling elements. 
 
     
     
       9. The antenna apparatus as claimed in  claim 8 , further comprising, at a plurality of positions of the respective first portions of the first and second base radiation elements:
 a plurality of second coupling elements extending along the second base radiation element and integrally formed with the second base radiation element; and 
 a plurality of third coupling elements extending along the first base radiation element and integrally formed with the first base radiation element, 
 wherein the plurality of second coupling elements are capacitively coupled to the plurality of third coupling elements, respectively. 
 
     
     
       10. The antenna apparatus as claimed in  claim 9 , further comprising, in one of a first case that two adjacent second coupling elements among the plurality of second coupling elements have different widths in a direction orthogonal to the first direction, and a second case that two adjacent third coupling elements among the plurality of third coupling elements have different widths in the direction orthogonal to the first direction:
 a fourth coupling element between the two adjacent second coupling elements or between the two adjacent third coupling elements, the fourth coupling element having a width continuously changing in the direction orthogonal to the first direction. 
 
     
     
       11. The antenna apparatus as claimed in  claim 10 , further comprising:
 a ground conductor; and 
 a fifth coupling element extending along the first base radiation element and integrally formed with the first base radiation element, 
 wherein the fifth coupling element is capacitively coupled to the ground conductor. 
 
     
     
       12. The antenna apparatus as claimed in  claim 10 , further comprising:
 a ground conductor; and 
 a sixth coupling element extending along at least one of the first and second branch radiation elements and integrally formed with the at least one of the first and second branch radiation elements, 
 wherein the sixth coupling element is capacitively coupled to the ground conductor. 
 
     
     
       13. The antenna apparatus as claimed in  claim 7 , further comprising:
 a dielectric substrate having a first side and a second side, 
 wherein the first base radiation element includes a portion formed on the first side; and a through-hole conductor penetrating from the first side to the second side, 
 wherein the third branch radiation element and the second coupling element are formed on the first side, 
 wherein the second base radiation element, the first and second branch radiation elements, and the first coupling element are formed on the second side, and 
 wherein the first branch point is provided on the second side at a position of the through-hole conductor. 
 
     
     
       14. The antenna apparatus as claimed in  claim 7 , further comprising:
 a dielectric substrate having a first side and a second side, 
 wherein the first base radiation element is formed on the first side, 
 wherein the second base radiation element and the first and second coupling elements are formed on the second side, and 
 wherein each of the first, second, and third branch radiation elements includes a portion formed on the first side and a portion formed on the second side, and the portions formed on the first side are connected to the portions formed on the second side by a plurality of through-hole conductors penetrating from the first side to the second side. 
 
     
     
       15. The antenna apparatus as claimed in  claim 13 , further comprising a third coupling element formed on the first side, the third coupling element extending along the first base radiation element and integrally formed with the first base radiation element,
 wherein the third coupling element is capacitively coupled to at least one of the first and second coupling elements. 
 
     
     
       16. The antenna apparatus as claimed in  claim 13 , further comprising a planar radiation element provided perpendicular to the dielectric substrate, and electrically connected to at least one of the first, second, and third branch radiation elements. 
     
     
       17. The antenna apparatus as claimed in  claim 13 , further comprising a ground conductor,
 wherein the ground conductor includes a portion formed on the first side, and a portion formed on the second side, and the portion formed on the first side are connected to the portion formed on the second side by a plurality of through-hole conductors penetrating from the first side to the second side. 
 
     
     
       18. A wireless communication apparatus comprising an antenna apparatus, the antenna apparatus comprising:
 a feed point; 
 a ground point; 
 a first base radiation element and a second base radiation element; and 
 a connecting element, 
 wherein the first base radiation element has a first end and a second end opposite to the first end, and extends between the first and second ends of the first base radiation element, the first end of the first base radiation element is connected to the feed point, and the first base radiation element includes a first portion extending in a +x direction, and a second portion including the second end of the first base radiation element, and the second portion extends in a +z direction and a +y direction continuously, 
 wherein the second base radiation element has a third end and a fourth end opposite to the third end, and extends between the third and fourth ends of the second base radiation element, the third end of the second base radiation element is connected to the ground point, the second base radiation element includes a third portion extending in the +x direction, and a fourth portion including the fourth end of the second base radiation element, and the fourth portion extends in the +x direction and the +z direction continuously, 
 wherein the first end of the first base radiation element is closer to the third end of the second base radiation element than to the fourth end of the second base radiation element, and the second end of the first base radiation element is closer to the fourth end of the second base radiation element than to the third end of the second base radiation element, 
 wherein the first portions of the first base radiation element and the third portion of second base radiation element are parallel to each other and spaced at a predetermined distance from each other in the +y direction, 
 wherein the connecting element has a fifth end and a sixth end opposite to the fifth end, and extends between the fifth and sixth ends of the connecting element, the fifth end of the connecting element is connected directly to the second end of the first base radiation elements, the sixth end of the connecting element is connected directly to the fourth end of the second base radiation element and the connecting element extends in the +x direction, and 
 wherein the second portion of the first and second base radiation element, the fourth portion of the second base radiation element and the connecting element constitute a loop configuration electrically, and the first and second base radiation elements are electrically connected to each other only through the connecting element. 
 
     
     
       19. An electronic device comprising an antenna apparatus, the antenna apparatus comprising:
 a feed point; 
 a ground point; 
 a first base radiation element and a second base radiation element; and 
 a connecting element, 
 wherein the first base radiation element has a first end and a second end opposite to the first end, and extends between the first and second ends of the first base radiation element, the first end of the first base radiation element is connected to the feed point, and the first base radiation element includes a first portion extending in a +x direction, and a second portion including the second end of the first base radiation element, and the second portion extends in a +z direction and a +y direction continuously, 
 wherein the second base radiation element has a third end and a fourth end opposite to the third end, and extends between the third and fourth ends of the second base radiation element, the third end of the second base radiation element is connected to the ground point, the second base radiation element includes a third portion extending in the +x direction, and a fourth portion including the fourth end of the second base radiation element, and the fourth portion extends in the +x direction and the +z direction continuously, 
 wherein the first end of the first base radiation element is closer to the third end of the second base radiation element than to the fourth end of the second base radiation element, and the second end of the first base radiation element is closer to the fourth end of the second base radiation element than to the third end of the second base radiation element, 
 wherein the first portions of the first base radiation element and the third portion of second base radiation element are parallel to each other and spaced at a predetermined distance from each other in the +y direction, 
 wherein the connecting element has a fifth end and a sixth end opposite to the fifth end, and extends between the fifth and sixth ends of the connecting element, the fifth end of the connecting element is connected directly to the second end of the first base radiation elements, the sixth end of the connecting element is connected directly to the fourth end of the second base radiation element and the connecting element extends in the +x direction, and 
 wherein the second portion of the first and second base radiation element, the fourth portion of the second base radiation element and the connecting element constitute a loop configuration electrically, and the first and second base radiation elements are electrically connected to each other only through the connecting element.